The present invention relates to a process and apparatus for heating the passenger compartment of a motor vehicle, and more particularly to a process and apparatus for heating the passenger compartment of an electric vehicle.
In motor vehicles having a combustion engine, the waste heat from the engine is used for heating purposes, so that sufficient heat energy is generally available under virtually all operating conditions. Although in damp or dank weather the windows of a motor vehicle can generally be prevented from misting up by suitably strong heating of the passenger compartment, the heating energy required for this purpose is only available after the vehicle has been operated for a long period of time. Immediately after the combustion engine is started up, misting of the windows, accompanied by icing-up under very low external temperatures, is therefore often inevitable. Despite this, the vehicle is often set in motion without any regard being paid to the considerable visual obstruction created and to the danger accompanying the operation of a vehicle so affected. In electric vehicles specifically, in which only a small amount of waste heat is available to heat up the passenger compartment, the internal misting and, where appropriate, internal icing-up of the vehicle's windows represents a considerable problem which impairs traffic safety. Although a more rapid heating of the passenger compartment can be achieved by utilizing appropriate electrical heating devices, a considerable quantity of electrical energy is required by such devices, placing a corresponding load on the batteries and possibly leading to a severe curtailment of the vehicle's operating range. During winter operation in particular, the capacity of the batteries is in any case restricted by the cold, and any necessary heating of the passenger compartment adversely restricts the capacity for use of an electric vehicle.